I used to haul hay on the weekends home from college, working for my BIL whose family had a haying/fencing business. While I would wear a short sleeved t-shirt, they wore long sleeved cowboy-style shirts with a tshirt on underneath.   They told me their sweat kept them cooler and I tried it out and it was true.

I've worked construction, usually industrial-type construction (refineries, building pipeline compressor stations, etc.) and on the whole or average, it was harder than the roughnecking I had done, although the hardest days or nights on the drilling rigs was the hardest work I have ever done.

I got a part-time job while going to college, working at a candy factory in Amarillo (during the winter, when there was no hay hauling to be done back home). It was just a few hours a week and wasn't really worth the drive, so I didn't do it for too long. I did all kinds of manual labor stuff for them, but sometimes when I'd get there they'd have me putting suckers into boxes, hundreds at a time with a plastic scoop, much like a big grain scoop. Yes, I shoveled suckers.